1. Field of the Invention
The present invention relates to an object, a method, or a manufacturing method. The present invention relates to a process, a machine, manufacture, or a composition of matter. One embodiment of the present invention relates to a semiconductor device, a display device, a light-emitting device, a power storage device, an imaging device, a driving method thereof, or a manufacturing method thereof. In particular, one embodiment of the present invention relates to an electronic device.
Note that electronic devices in this specification mean all devices including secondary batteries, and electro-optical devices including secondary batteries, information terminal devices including secondary batteries, vehicles including secondary batteries, and the like are all electronic devices.
2. Description of the Related Art
In recent years, portable information terminals typified by smartphones have been actively developed. Portable information terminals, which are a kind of electronic devices, are desired to be lightweight and compact for users.
Patent Document 1 discloses an example of a hands-free wearable device with which information can be visually obtained anywhere, specifically, a goggle-type display device that includes a CPU and allows data communication. The device disclosed in Patent Document 1 is also a kind of electronic device.
Most wearable devices and portable information terminals include secondary batteries that can be repeatedly charged and discharged, and have problems in that there is a limitation on the operation time because their lightweight and compactness cost the battery capacity. Secondary batteries used in wearable devices and portable information terminals should be lightweight and compact and should stand long-time use.
Examples of the secondary batteries include a nickel-metal hydride battery and a lithium-ion secondary battery. In particular, lithium-ion secondary batteries have been actively developed because the capacity thereof can be increased and the size thereof can be reduced.
Electrodes serving as positive electrodes or negative electrodes of lithium-ion secondary batteries are each formed using, for example, metallic lithium, a carbon-based material, or an alloy-based material.